1. Technical Field
The present invention relates to an image forming optical element which can be applied, for example, to scanner devices, and more particularly to an image forming optical element having an image forming optical system and a light shielding member.
2. Related Art
In image scanners, facsimiles, copying machines, financial terminal devices and the like, a contact image sensor modules (hereinafter, referred to as “CISM”) is known as an image reading device. In this type of image reading device, SLA (SELFOC (registered trademark) lens array), for example, is generally disposed between a reading object and an optical sensor so that an optical image of the reading object is correctly incident on each of a plurality of fine optical sensors that are arranged in line so as to form an optical image on the optical sensor. JP-A-2009-246623 describes that a lens array and an aperture members (light shielding members) having through holes that correspond to the respective lens configuration are disposed in place of the SLA.
As higher precise image is required, the through holes of the light shielding member becomes finer. Meanwhile, it becomes difficult to manufacture such fine through holes having a uniform cross section. For example, when the light shielding member is manufactured by using a mold, the wall of the through hole must be tapered in order to ensure the separation of the product from the mold. Such a taper may effect on the performance of the light shielding member, and specifically on the quality of resultant image. However, this problem has not been so far adequately addressed.